diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/proc.rst | 44 | ||||
| -rw-r--r-- | Documentation/filesystems/vfs.rst | 105 |
2 files changed, 109 insertions, 40 deletions
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 9d5fd9424e8b..59db0bed35e1 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -85,7 +85,7 @@ contact Bodo Bauer at bb@ricochet.net. We'll be happy to add them to this document. The latest version of this document is available online at -http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.html +https://www.kernel.org/doc/html/latest/filesystems/proc.html If the above direction does not works for you, you could try the kernel mailing list at linux-kernel@vger.kernel.org and/or try to reach me at @@ -232,7 +232,7 @@ asynchronous manner and the value may not be very precise. To see a precise snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table. It's slow but very precise. -.. table:: Table 1-2: Contents of the status files (as of 4.19) +.. table:: Table 1-2: Contents of the status fields (as of 4.19) ========================== =================================================== Field Content @@ -305,7 +305,7 @@ It's slow but very precise. ========================== =================================================== -.. table:: Table 1-3: Contents of the statm files (as of 2.6.8-rc3) +.. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3) ======== =============================== ============================== Field Content @@ -323,7 +323,7 @@ It's slow but very precise. ======== =============================== ============================== -.. table:: Table 1-4: Contents of the stat files (as of 2.6.30-rc7) +.. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7) ============= =============================================================== Field Content @@ -1321,9 +1321,9 @@ many times the slaves link has failed. 1.4 SCSI info ------------- -If you have a SCSI host adapter in your system, you'll find a subdirectory -named after the driver for this adapter in /proc/scsi. You'll also see a list -of all recognized SCSI devices in /proc/scsi:: +If you have a SCSI or ATA host adapter in your system, you'll find a +subdirectory named after the driver for this adapter in /proc/scsi. +You'll also see a list of all recognized SCSI devices in /proc/scsi:: >cat /proc/scsi/scsi Attached devices: @@ -1449,16 +1449,18 @@ Various pieces of information about kernel activity are available in the since the system first booted. For a quick look, simply cat the file:: > cat /proc/stat - cpu 2255 34 2290 22625563 6290 127 456 0 0 0 - cpu0 1132 34 1441 11311718 3675 127 438 0 0 0 - cpu1 1123 0 849 11313845 2614 0 18 0 0 0 - intr 114930548 113199788 3 0 5 263 0 4 [... lots more numbers ...] - ctxt 1990473 - btime 1062191376 - processes 2915 - procs_running 1 + cpu 237902850 368826709 106375398 1873517540 1135548 0 14507935 0 0 0 + cpu0 60045249 91891769 26331539 468411416 495718 0 5739640 0 0 0 + cpu1 59746288 91759249 26609887 468860630 312281 0 4384817 0 0 0 + cpu2 59489247 92985423 26904446 467808813 171668 0 2268998 0 0 0 + cpu3 58622065 92190267 26529524 468436680 155879 0 2114478 0 0 0 + intr 8688370575 8 3373 0 0 0 0 0 0 1 40791 0 0 353317 0 0 0 0 224789828 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 190974333 41958554 123983334 43 0 224593 0 0 0 <more 0's deleted> + ctxt 22848221062 + btime 1605316999 + processes 746787147 + procs_running 2 procs_blocked 0 - softirq 183433 0 21755 12 39 1137 231 21459 2263 + softirq 12121874454 100099120 3938138295 127375644 2795979 187870761 0 173808342 3072582055 52608 224184354 The very first "cpu" line aggregates the numbers in all of the other "cpuN" lines. These numbers identify the amount of time the CPU has spent performing @@ -1520,8 +1522,8 @@ softirq. Information about mounted ext4 file systems can be found in /proc/fs/ext4. Each mounted filesystem will have a directory in /proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or -/proc/fs/ext4/dm-0). The files in each per-device directory are shown -in Table 1-12, below. +/proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device +directory are shown in Table 1-12, below. .. table:: Table 1-12: Files in /proc/fs/ext4/<devname> @@ -1601,12 +1603,12 @@ can inadvertently disrupt your system, it is advisable to read both documentation and source before actually making adjustments. In any case, be very careful when writing to any of these files. The entries in /proc may change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt -review the kernel documentation in the directory /usr/src/linux/Documentation. +review the kernel documentation in the directory linux/Documentation. This chapter is heavily based on the documentation included in the pre 2.2 kernels, and became part of it in version 2.2.1 of the Linux kernel. -Please see: Documentation/admin-guide/sysctl/ directory for descriptions of these -entries. +Please see: Documentation/admin-guide/sysctl/ directory for descriptions of +these entries. Summary ------- diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index f3b344f0c0a4..769be5230210 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -107,7 +107,7 @@ file /proc/filesystems. struct file_system_type ----------------------- -This describes the filesystem. As of kernel 2.6.39, the following +This describes the filesystem. The following members are defined: .. code-block:: c @@ -115,14 +115,24 @@ members are defined: struct file_system_type { const char *name; int fs_flags; + int (*init_fs_context)(struct fs_context *); + const struct fs_parameter_spec *parameters; struct dentry *(*mount) (struct file_system_type *, int, - const char *, void *); + const char *, void *); void (*kill_sb) (struct super_block *); struct module *owner; struct file_system_type * next; - struct list_head fs_supers; + struct hlist_head fs_supers; + struct lock_class_key s_lock_key; struct lock_class_key s_umount_key; + struct lock_class_key s_vfs_rename_key; + struct lock_class_key s_writers_key[SB_FREEZE_LEVELS]; + + struct lock_class_key i_lock_key; + struct lock_class_key i_mutex_key; + struct lock_class_key invalidate_lock_key; + struct lock_class_key i_mutex_dir_key; }; ``name`` @@ -132,6 +142,15 @@ members are defined: ``fs_flags`` various flags (i.e. FS_REQUIRES_DEV, FS_NO_DCACHE, etc.) +``init_fs_context`` + Initializes 'struct fs_context' ->ops and ->fs_private fields with + filesystem-specific data. + +``parameters`` + Pointer to the array of filesystem parameters descriptors + 'struct fs_parameter_spec'. + More info in Documentation/filesystems/mount_api.rst. + ``mount`` the method to call when a new instance of this filesystem should be mounted @@ -148,7 +167,11 @@ members are defined: ``next`` for internal VFS use: you should initialize this to NULL - s_lock_key, s_umount_key: lockdep-specific +``fs_supers`` + for internal VFS use: hlist of filesystem instances (superblocks) + + s_lock_key, s_umount_key, s_vfs_rename_key, s_writers_key, + i_lock_key, i_mutex_key, invalidate_lock_key, i_mutex_dir_key: lockdep-specific The mount() method has the following arguments: @@ -222,33 +245,42 @@ struct super_operations ----------------------- This describes how the VFS can manipulate the superblock of your -filesystem. As of kernel 2.6.22, the following members are defined: +filesystem. The following members are defined: .. code-block:: c struct super_operations { struct inode *(*alloc_inode)(struct super_block *sb); void (*destroy_inode)(struct inode *); + void (*free_inode)(struct inode *); void (*dirty_inode) (struct inode *, int flags); - int (*write_inode) (struct inode *, int); - void (*drop_inode) (struct inode *); - void (*delete_inode) (struct inode *); + int (*write_inode) (struct inode *, struct writeback_control *wbc); + int (*drop_inode) (struct inode *); + void (*evict_inode) (struct inode *); void (*put_super) (struct super_block *); int (*sync_fs)(struct super_block *sb, int wait); + int (*freeze_super) (struct super_block *); int (*freeze_fs) (struct super_block *); + int (*thaw_super) (struct super_block *); int (*unfreeze_fs) (struct super_block *); int (*statfs) (struct dentry *, struct kstatfs *); int (*remount_fs) (struct super_block *, int *, char *); - void (*clear_inode) (struct inode *); void (*umount_begin) (struct super_block *); int (*show_options)(struct seq_file *, struct dentry *); + int (*show_devname)(struct seq_file *, struct dentry *); + int (*show_path)(struct seq_file *, struct dentry *); + int (*show_stats)(struct seq_file *, struct dentry *); ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t); ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t); - int (*nr_cached_objects)(struct super_block *); - void (*free_cached_objects)(struct super_block *, int); + struct dquot **(*get_dquots)(struct inode *); + + long (*nr_cached_objects)(struct super_block *, + struct shrink_control *); + long (*free_cached_objects)(struct super_block *, + struct shrink_control *); }; All methods are called without any locks being held, unless otherwise @@ -269,6 +301,11 @@ or bottom half). ->alloc_inode was defined and simply undoes anything done by ->alloc_inode. +``free_inode`` + this method is called from RCU callback. If you use call_rcu() + in ->destroy_inode to free 'struct inode' memory, then it's + better to release memory in this method. + ``dirty_inode`` this method is called by the VFS when an inode is marked dirty. This is specifically for the inode itself being marked dirty, @@ -296,8 +333,12 @@ or bottom half). practice of using "force_delete" in the put_inode() case, but does not have the races that the "force_delete()" approach had. -``delete_inode`` - called when the VFS wants to delete an inode +``evict_inode`` + called when the VFS wants to evict an inode. Caller does + *not* evict the pagecache or inode-associated metadata buffers; + the method has to use truncate_inode_pages_final() to get rid + of those. Caller makes sure async writeback cannot be running for + the inode while (or after) ->evict_inode() is called. Optional. ``put_super`` called when the VFS wishes to free the superblock @@ -308,14 +349,25 @@ or bottom half). superblock. The second parameter indicates whether the method should wait until the write out has been completed. Optional. +``freeze_super`` + Called instead of ->freeze_fs callback if provided. + Main difference is that ->freeze_super is called without taking + down_write(&sb->s_umount). If filesystem implements it and wants + ->freeze_fs to be called too, then it has to call ->freeze_fs + explicitly from this callback. Optional. + ``freeze_fs`` called when VFS is locking a filesystem and forcing it into a consistent state. This method is currently used by the Logical - Volume Manager (LVM). + Volume Manager (LVM) and ioctl(FIFREEZE). Optional. + +``thaw_super`` + called when VFS is unlocking a filesystem and making it writable + again after ->freeze_super. Optional. ``unfreeze_fs`` called when VFS is unlocking a filesystem and making it writable - again. + again after ->freeze_fs. Optional. ``statfs`` called when the VFS needs to get filesystem statistics. @@ -324,22 +376,37 @@ or bottom half). called when the filesystem is remounted. This is called with the kernel lock held -``clear_inode`` - called then the VFS clears the inode. Optional - ``umount_begin`` called when the VFS is unmounting a filesystem. ``show_options`` - called by the VFS to show mount options for /proc/<pid>/mounts. + called by the VFS to show mount options for /proc/<pid>/mounts + and /proc/<pid>/mountinfo. (see "Mount Options" section) +``show_devname`` + Optional. Called by the VFS to show device name for + /proc/<pid>/{mounts,mountinfo,mountstats}. If not provided then + '(struct mount).mnt_devname' will be used. + +``show_path`` + Optional. Called by the VFS (for /proc/<pid>/mountinfo) to show + the mount root dentry path relative to the filesystem root. + +``show_stats`` + Optional. Called by the VFS (for /proc/<pid>/mountstats) to show + filesystem-specific mount statistics. + ``quota_read`` called by the VFS to read from filesystem quota file. ``quota_write`` called by the VFS to write to filesystem quota file. +``get_dquots`` + called by quota to get 'struct dquot' array for a particular inode. + Optional. + ``nr_cached_objects`` called by the sb cache shrinking function for the filesystem to return the number of freeable cached objects it contains. |