diff options
Diffstat (limited to 'Documentation/filesystems/vfs.txt')
| -rw-r--r-- | Documentation/filesystems/vfs.txt | 48 |
1 files changed, 25 insertions, 23 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index bc4b06b3160..1f0ba30ae47 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -360,6 +360,8 @@ struct inode_operations { int (*removexattr) (struct dentry *, const char *); void (*update_time)(struct inode *, struct timespec *, int); int (*atomic_open)(struct inode *, struct dentry *, + int (*tmpfile) (struct inode *, struct dentry *, umode_t); +} ____cacheline_aligned; struct file *, unsigned open_flag, umode_t create_mode, int *opened); }; @@ -472,6 +474,9 @@ otherwise noted. component is negative or needs lookup. Cached positive dentries are still handled by f_op->open(). + tmpfile: called in the end of O_TMPFILE open(). Optional, equivalent to + atomically creating, opening and unlinking a file in given directory. + The Address Space Object ======================== @@ -549,7 +554,7 @@ struct address_space_operations ------------------------------- This describes how the VFS can manipulate mapping of a file to page cache in -your filesystem. As of kernel 2.6.22, the following members are defined: +your filesystem. The following members are defined: struct address_space_operations { int (*writepage)(struct page *page, struct writeback_control *wbc); @@ -566,7 +571,7 @@ struct address_space_operations { loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata); sector_t (*bmap)(struct address_space *, sector_t); - int (*invalidatepage) (struct page *, unsigned long); + void (*invalidatepage) (struct page *, unsigned int, unsigned int); int (*releasepage) (struct page *, int); void (*freepage)(struct page *); ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, @@ -685,14 +690,14 @@ struct address_space_operations { invalidatepage: If a page has PagePrivate set, then invalidatepage will be called when part or all of the page is to be removed from the address space. This generally corresponds to either a - truncation or a complete invalidation of the address space - (in the latter case 'offset' will always be 0). - Any private data associated with the page should be updated - to reflect this truncation. If offset is 0, then - the private data should be released, because the page - must be able to be completely discarded. This may be done by - calling the ->releasepage function, but in this case the - release MUST succeed. + truncation, punch hole or a complete invalidation of the address + space (in the latter case 'offset' will always be 0 and 'length' + will be PAGE_CACHE_SIZE). Any private data associated with the page + should be updated to reflect this truncation. If offset is 0 and + length is PAGE_CACHE_SIZE, then the private data should be released, + because the page must be able to be completely discarded. This may + be done by calling the ->releasepage function, but in this case the + release MUST succeed. releasepage: releasepage is called on PagePrivate pages to indicate that the page should be freed if possible. ->releasepage @@ -777,7 +782,7 @@ struct file_operations { ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *); ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t); - int (*readdir) (struct file *, void *, filldir_t); + int (*iterate) (struct file *, struct dir_context *); unsigned int (*poll) (struct file *, struct poll_table_struct *); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); @@ -815,7 +820,7 @@ otherwise noted. aio_write: called by io_submit(2) and other asynchronous I/O operations - readdir: called when the VFS needs to read the directory contents + iterate: called when the VFS needs to read the directory contents poll: called by the VFS when a process wants to check if there is activity on this file and (optionally) go to sleep until there @@ -901,10 +906,8 @@ defined: struct dentry_operations { int (*d_revalidate)(struct dentry *, unsigned int); int (*d_weak_revalidate)(struct dentry *, unsigned int); - int (*d_hash)(const struct dentry *, const struct inode *, - struct qstr *); - int (*d_compare)(const struct dentry *, const struct inode *, - const struct dentry *, const struct inode *, + int (*d_hash)(const struct dentry *, struct qstr *); + int (*d_compare)(const struct dentry *, const struct dentry *, unsigned int, const char *, const struct qstr *); int (*d_delete)(const struct dentry *); void (*d_release)(struct dentry *); @@ -949,25 +952,24 @@ struct dentry_operations { d_hash: called when the VFS adds a dentry to the hash table. The first dentry passed to d_hash is the parent directory that the name is - to be hashed into. The inode is the dentry's inode. + to be hashed into. Same locking and synchronisation rules as d_compare regarding what is safe to dereference etc. d_compare: called to compare a dentry name with a given name. The first dentry is the parent of the dentry to be compared, the second is - the parent's inode, then the dentry and inode (may be NULL) of the - child dentry. len and name string are properties of the dentry to be - compared. qstr is the name to compare it with. + the child dentry. len and name string are properties of the dentry + to be compared. qstr is the name to compare it with. Must be constant and idempotent, and should not take locks if - possible, and should not or store into the dentry or inodes. - Should not dereference pointers outside the dentry or inodes without + possible, and should not or store into the dentry. + Should not dereference pointers outside the dentry without lots of care (eg. d_parent, d_inode, d_name should not be used). However, our vfsmount is pinned, and RCU held, so the dentries and inodes won't disappear, neither will our sb or filesystem module. - ->i_sb and ->d_sb may be used. + ->d_sb may be used. It is a tricky calling convention because it needs to be called under "rcu-walk", ie. without any locks or references on things. |